Are there any resources in particular you'd recommend discussing what to avoid in Perl on a 64-bit machine?
Don't use source filters. Also, don't use threads. Keep away from extensions written in C, since most C programmers still can't understand why they shouldn't store pointers in INTs.
More generally, (system) threads are a bad solution for most problems. If you want to download a lot of files, for instance, you'll be better served using asynchronous calls than threads. For starters, your programs won't crash.
Edit: use something like this instead: forks
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